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211.
212.
数值模拟和卫星反演大气能见度对比分析 总被引:1,自引:0,他引:1
对2004年4月11日、2005年3月9日和2005年3月27日发生在黄渤海海域3个典型海雾个例数值模拟得到的大气能见度与可见光卫星云图的反照率进行对比分析,利用不同时刻大气能见度与反照率的对应关系进行线性数学拟合,得到新的适合白昼的大气能见度反演公式。利用该公式反演了几次显著海雾过程的大气能见度分布,发现海雾预报系统对大气能见度<200 m的海上浓雾的面积预报准确率约90%左右。对发生在2009年3月1日到2010年5月21日期间的46次较强海雾进行了初步统计,从判别海雾有无的角度来看该海雾预报系统对海雾的预报准确率为91.3%。 相似文献
213.
Koji Fujita 《水文研究》2007,21(21):2892-2896
The impact of the timing of dust deposition on glacier runoff was evaluated using a glacier mass‐balance model with a newly improved scheme to track a dusted layer in a snow layer of a glacier. The lowering of surface albedo due to the dusted layer appearing leads to a drastic increase of glacier runoff even under the same meteorological conditions. Calculations of seasonal sensitivity, the relationship between dusted date and resulting runoff, have shown that dust deposition during a melting season might cause a drastic mass outflow from a glacier through changing the surface albedo during the melting season. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
214.
Black carbon aerosols and their radiative properties in the Pearl River Delta region 总被引:13,自引:0,他引:13
Dui Wu JieTai Mao XueJiao Deng XueXi Tie YuanHang Zhang LiMin Zeng Fei Li HaoBo Tan XueYan Bi XiaoYing Huang Jing Chen Tao Deng 《中国科学D辑(英文版)》2009,52(8):1152-1163
The climatic and environmental effects of atmospheric aerosols are a hot topic in global science community, and radiative
properties of the aerosols are one of the important parameters in assessing climatic change. Here we studied the black carbon
concentration and absorption coefficient measured with aethalometers, scattering coefficient measured with nephelometers,
and single scattering albedo derived at an atmospheric composition watch station in Guangzhou from 2004 to 2007. Our main
results are as follows. The data of black carbon concentration and absorption coefficients measured with instruments cannot
be directly used until they are measured in parallel with internationally accepted instruments for comparison, calibration,
and reduction. After evaluation of the data, the result shows that the monthly mean of BC concentration varies 3.1–14.8 μg·m−3 and the concentration decreases by about 1 μg·m−3 in average over the four years; It is higher in the dry season with a multi-year mean of 8.9 μg/m3 and lower in the rainy season with a multi-year mean of 8.0 μg·m−3; The extreme maximum of monthly mean concentration occurred in December 2004 and extreme minimum in July 2007, and a 4-year
mean is 8.4 μg·m−3. It is also shown that monthly mean scattering coefficient derived varies 129 −565 Mm−1, monthly mean absorption coefficient 32–139 Mm−1, and monthly mean single scattering albedo 0.71–0.91, with annual mean values of 0.80, 0.82, 0.79 and 0.84 for 2004, 2005,
2006 and 2007, respectively. Three instruments were used to take simultaneous measurements of BC in PM10, PM2.5, and PM1 and the results showed that PM2.5 took up about 90% of PM10 and PM1 accounted for about 68% of PM2.5, and BC aerosols are mainly present in fine particulates. The variability of BC concentrations is quite consistent between
the Nancun station (141 m above sea level) and the Panyu station (13 m above sea level), which are 8 km apart from each other.
The concentration in higher altitude station (Panyu) is consistently lower than the lower altitude station (Nancun), and the
difference of annual mean is about 4 μg·m−3.
Supported by Natural Science Foundation of China (Grant Nos. U0733004, 40375002, 40418008, 40775011), National High Technology
R & D Program of China (Grant Nos. 2006AA06A306 and 2006AA06A308) and National Basic Research Program of China (Grant No.
2005CB422207) 相似文献
215.
An evaluation of Arctic cloud and radiation processes during the SHEBA year: simulation results from eight Arctic regional climate models 总被引:1,自引:1,他引:0
K. Wyser C. G. Jones P. Du E. Girard U. Willén J. Cassano J. H. Christensen J. A. Curry K. Dethloff J.-E. Haugen D. Jacob M. Køltzow R. Laprise A. Lynch S. Pfeifer A. Rinke M. Serreze M. J. Shaw M. Tjernström M. Zagar 《Climate Dynamics》2008,30(2-3):203-223
Eight atmospheric regional climate models (RCMs) were run for the period September 1997 to October 1998 over the western Arctic
Ocean. This period was coincident with the observational campaign of the Surface Heat Budget of the Arctic Ocean (SHEBA) project.
The RCMs shared common domains, centred on the SHEBA observation camp, along with a common model horizontal resolution, but
differed in their vertical structure and physical parameterizations. All RCMs used the same lateral and surface boundary conditions.
Surface downwelling solar and terrestrial radiation, surface albedo, vertically integrated water vapour, liquid water path
and cloud cover from each model are evaluated against the SHEBA observation data. Downwelling surface radiation, vertically
integrated water vapour and liquid water path are reasonably well simulated at monthly and daily timescales in the model ensemble
mean, but with considerable differences among individual models. Simulated surface albedos are relatively accurate in the
winter season, but become increasingly inaccurate and variable in the melt season, thereby compromising the net surface radiation
budget. Simulated cloud cover is more or less uncorrelated with observed values at the daily timescale. Even for monthly averages,
many models do not reproduce the annual cycle correctly. The inter-model spread of simulated cloud-cover is very large, with
no model appearing systematically superior. Analysis of the co-variability of terms controlling the surface radiation budget
reveal some of the key processes requiring improved treatment in Arctic RCMs. Improvements in the parameterization of cloud
amounts and surface albedo are most urgently needed to improve the overall performance of RCMs in the Arctic. 相似文献
216.
利用MODIS卫星资料反演中国地区晴空地表短波反照率及其特征分析 总被引:16,自引:0,他引:16
利用MODIS地表双向反照率产品(MOD43B1),结合地表海拔高度和地表覆盖类型资料,计算并分析了中国地区晴空反照率的时空分布,以及地表反照率与地形和地表覆盖的关系.首先,利用改则自动气象站的地基观测对MODIS地表反照率进行了对比验证.验证结果表明卫星观测可以较好地反映反照率随时间的变化,MODIS地表反照率与地表实测反照率符合较好.年平均地表反照率与海拔高度有很好的相关,反照率的高值出现在高海拔山区.冬春季节,我国高海拔山区因积雪覆盖成为反照率的高值区;夏秋季节,地表反照率主要受地表土壤湿度和植被盖度的影响,沙地和沙漠地带反照率最高.最后,计算了中国典型地表类型的反照率随时间的变化,结果表明大部分地表类型的反照率具有较大的时间变化,地表反照率在春秋季节较大,夏季反照率较小. 相似文献
217.
MODIS反照率产品在模拟北京气温中的应用 总被引:2,自引:1,他引:1
地表反照率是制约地表能量收支平衡的基本因子,其变化会影响气温和降水等气象要素,进而影响区域乃至全球的气候。文中使用WRF模式,设计两组反照率敏感试验,探讨地表反照率参数对近地面2处气温模拟精度的影响。结果表明:(1)当北京地区地表反照率增大(减小)0.05时,气温相应降低(升高)0.1~0.5 K,气温变化从城区到郊区有一个明显的降幅,感热通量和潜热通量也相应减小(增大),且变幅主要为0~13 W/m2;(2)将控制试验和MODIS反照率敏感试验模拟结果与实况对比分析发现,两种试验的模拟结果偏低,但应用卫星反照率产品后,气温升高约0.2~0.7 K,更接近实际,即应用MODIS反照率产品替换WRF模式中原有反照率能进一步提高气温的模拟精度。 相似文献
218.
Snow albedo is an important factor influencing the snow surface energy budget and snow melting,
yet uncertainties remain in the calculation of spectrally resolved snow surface albedo because the spectral
composition (visible versus near infrared) of the incident solar radiation is seldom available. The influence
of the spectral composition of the incoming solar radiation on the snow surface albedo, snow surface energy
budget, and final snow ablation is investigated through sensitivity experiments of four snow seasons at two
open sites in the Alps by using a multi-layer Snow-Atmosphere-Soil-Transfer scheme (SAST). Since the snow
albedo in the near infrared (NIR) spectral band is significantly lower than that in the visible (VIS) band,
and almost the entire NIR part of the solar radiation is absorbed in the top layer of the snow pack, given
a fixed amount of incoming solar radiation, a lower VIS/NIR ratio implies that more NIR radiation is
reaching the ground surface and more is absorbed by the top layer of the snow pack, therefore, speeding
up the snow melting and increasing the surface runoff, although a lesser part of the solar radiation in
the visible band is transmitted into and trapped by the sub-layer of the snow pack. The above VIS/NIR ratio
effect of the incoming solar radiation can result in a couple of days difference in the timing of snow
ablation and it becomes more significant in late spring when the total solar radiation is intensified with
seasonal evolution. Snow aging also slightly intensifies this VIS/NIR ratio effect. 相似文献
219.
沙尘气溶胶辐射强迫全球分布的模拟研究 总被引:7,自引:2,他引:5
为了定景了解沙尘气溶胶对气候的影响,文中利用一个改进的辐射传输模式,结合伞球气溶胶数据集(G-ADS),计算了晴空条件下,冬夏两季沙尘气溶胶的直接辐射强迫在对流层顶和地面的全球分布,并讨论了云对沙尘气溶胶辐射强迫的影响.计算结果表明,对北半球冬季和夏季而言,在对流层顶沙尘气溶胶的全球短波辐射强迫的平均值分别为-0.477和-0.501 W/m2;长波辐射强迫分别为0.11和0.085 W/m2;全球平均短波地面辐射强迫冬夏两季分别为-1.362和-1.559 W/m2;长波辐射强迫分别为0.274和0.23 W/m2.沙尘气溶胶在对流层顶和地面的负辐射强迫的绝对值郁随太阳天顶角的余弦和地表反照率的增加而增大;地表反照率对沙尘气溶胶辐射强迫的强度和分布都有重要影响.研究指出:云对沙尘气溶胶的直接辐射强迫的影响不仅取决于云量,而且取决于云的高度和云水路径,以及地面反照率和太阳高度角等综合因素.中云和低云对沙尘气溶胶在对流层顶的短波辐射强迫的影响比高云明显.云的存在都使对流层顶长波辐射强迫减少,其中低云的影响最为明显.因此,在估算沙尘气溶胶总的直接辐射强迫时,云的贡献不可忽视. 相似文献
220.
应用MODIS地表反照率产品MCD43C3,结合青藏高原自然带数据、积雪覆盖率和植被指数数据,采用一元线性回归方法分析了2000~2016年青藏高原地表反照率的分布及变化特征,结果表明:1)高原地表反照率空间分布差异大,整体上东南部低、西北部高,受地形和地表覆盖影响较大。2)高原地表反照率四季的空间分布变化明显,高海拔山脉和高寒灌丛草甸是高原地表反照率年内和年际变化的敏感地区。3)高原地表反照率年变化介于0.19~0.26,一定程度上表现为“双峰单谷”型,与地表覆盖类型的季节变化密切相关。4)高原地表反照率年际变化整体呈缓慢波动减小的趋势,平均变率约为-0.4×10-3 a-1,减小的区域约占高原总面积的66%,川西 —藏东针叶林带的西南部地区减小得最快,减小速率超过1.0×10-2 a-1。5)高原地表反照率减小与冰川消融和积雪减少密切相关,高原植被覆盖改善也是一个重要因素。 相似文献